Metallurgical process.



0. B. DAWSON. METALLURGICAL PROCESS.

APPLICATION FILED JULY H. 1917- 1,277,047; Patented Aug. 27, 1918.

I Oliverfiflawsom 5y I orrvnn B. DAWSON, or EL Peso, TEXAS, ASSIGNOR T DAWSON METALLURGICAL summon COMPANY, A CORPORATION or ARIZONA.

METALLURGICAL PROCESS.

To all whom it may concern:

Be it known that I, OLIVER B. DAWSON, a citizen of the United States, residing at El Paso, in the county of El Paso and State .of Texas, have invented certain new and useful Improvements in Metallurgical Processes; and I do hereby declare the following to be a full, clear, and exact description of the in-.

vention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to metallurgical processes especially adapted to separating metals from their, ores when in an oxidized condition and has for its object to lessen the cost and to'render more eflicient than thesomewhat similar methods heretofore proposed A With these and other objects inview the invention consists in the novel steps and combinations of steps constituting the process all as will be more fully hereinafter disclosed and particularly pointed out. in the claims.

Referring to the accompanying drawings forming a part of this specification inwhich trated in said like numerals designate like partsin all the views p Figure 1 is .a longitudinal sectional view of one type of furnace suitable for carrying Fig. 2 is a plan View of one of the port closures;

Fig. 3 is a sectional .view of the twyer cap shown in Fig. 2;

Fig. 4 is a view of the firing end of the furnace;

Fig. 5 is a sect'ionaLviewof shown in Fig. 4;

Fig. 6 is an enlarged detail view in section showing the discharge door and the furnace products car; and

Fig. 7 is a sectional View of the closure of the flue'chamber end of the furnace.

the parts 1 indicates any suitable furnace but preferably of the rotaryty e and of the general construction illustrate in my former Patent #936095, dated Oct. 5, 1909, and entitled metallurgical process.

But in order to carry out the present process I have added to the construction illuspatent the changes new to be disclosed. I

Referring more particularly to Figs i and Specification of Letters Patent. Patented Aug. 27, 1918- Applieation filed July 11, 1917. Serial No. 179,917.

5, I have added to the firing end of the furnace the valves 2, controlling the ports 3,

, leading through the closure member 4 into the furnace 1, and serving to control the esagainst the compression of said springs 6 as by-the nuts 10, or the pressure on said valves 2 maybe otherwise regulated by any suitable means not shown. 12 indicates the fuel inlet pipe or nozzle, 13 the usual refractory lin-,

the

ing, 14: the usual circular cap closing firing end of the'furnace, and 15 the usual twyers carried by said cap. The other parts of said furnace, not lettered, are or may be the same as in my said Patent #936095.

The furnce it will be seen is provided with an opening 16' closed by a door 17, and 45 represents a telescopic feed tube all as are disclosed in my patent above. Said furnace is also .provided with a discharge opening 20 closed by the door 21, and adapted to be brought into register with the product car 22, provided with the perforated doublebottom 23, and the steam or hot water supply pipe 24% opening into the space 25 between the bottom 26 and the perforated bottom 23 all for a purpose to be disclosed below.

The flue end 30 of the furnace is provided with the ring 31, having the circular annular chamber 32 filled wits asbestos 33. Said end 30 is closed by the disk like member 35 provided with the circular rib "or ring 36 adapted to enter said chamber 32 and to press tightly against the asbestos gasket or ring 33. Said member 35 is conveniently adjusted to and from said end 30 by means" of the threaded rod 36, socket 37, hand wheel 38 and nut 39 carried by the frame member 40. In carrying out the present invention I proceed as follows I I may take almost any metal voxid except those like iron, which'would form carbids under my process, and I subdivide them as by crushing, to'say one half inch mesh and without any admixture of flux or other ma-' terial I introduce said oxids into the furnace per whereupon the furnace is fired and the temperature raised to the reducing point of the ore being treated. Tf copper oxid is to be reduced, this said temperature will be say between 1600 F. and 1700 F. During this heating step of my process ll preferably slowly rotate the furnace so as to agitate or stir the ore, and the damper 35 is left open in order to permit the products of combustion to escape. When the ore has been thus brought to its reducing temperature the damper 35 is closed and the door 17 is opened, whereupon carbon, preferably in the form of charcoal, is fed into the furnace in quantities sufficient to reduce the charge to the metallic condition. The necessary quantity of carbon bein thus added to the ore in its heated condition, the furnace is now entirely closed to exclude the air, and upon slowly rotating the same a reaction occurs between the oxygen of the ore and the added carbon giving rise to the evolution of great quantities of carbon monoxid gas CO, and also to considerable heat.

The valves 2 being set at a predetermined pressure, say 15 pounds per square inch, if oxidized copper ores are being treated, the said, evolved gas will rise to said pressure on the interior of the furnace and said pressure will, inthe presence of the heat thus 6X0 thermically iven ofi, greatly accelerate the velocity of e reducing action in the furnace, and said pressure will cause the CO gas to penetrate to the minutest interstices of the heated ore, and thus greatly facilitate the reduction of the minutest particle of oxid to the metallic state. Tn practice I find the heat thus exothermically generated to be till ' toflotation in the separator.

ample to not only fuse substantially all the metal present 'in the ore, but it is also sufficient to render the freed metal so fluid as to cause it to change from the fibrous condition in which it is first released from the gangue to the globular or shotted condition. That is to say, I have found in practice if ore is reduced in a manner somewhat similar to that disclosed in my Patent #936095 above mentioned, but is not raised to a temperature as high as that produced by this process, then the freed metal will be found when cold to be associated with the gangue in a more or less fibrous condition, so that when the mass is crushed a greater or less portion of said metal is in such a fine state of subdivision as to entail considerable losses due 0n the other hand, when, the temperature is increased exothermically, as disclosed above, fibrous disposition of the metal is destroyed, the relatively high surface tension of the freed metal causes the individual fine particles to form globules, and the greater fluidity of the metal due to the higher temperature causes the individual globules to coalesce, or agglomerate into larger globules or the shot, so that when the mass produced by the present process is subsequently crushed, the

said globules or shot, or other masses of metal are found to be sufficiently large to cause them all to sink to the bottom of the concentrating device, with the result that a minimum loss of values due to flotation is had in the subsequent separation. This globulization or concentrating action is greatly facilitated by the stirring action to which the ore is subjected when rotating the furnace, for as each globule is thus brought mechanically into contact with another globule the two at once unite, owing to their fluidity to form a single and larger globule, and practice shows that this process continues until quite large particles are formed in some cases. a

The reducing action of the carbon and carbon monoxid continues until all the oxygen present is used up, and, all the metal is freed. When the reaction in the furnace thus ceases,v the attendant is made aware of it by the stoppage of the gas escaping past the valves 2. In other Words an unskilled observer may readily watch said valves and determine the end of the reaction or an automatic signal, (not'shown), may be associated with said valves to indicate that the reduction is complete.

After all the metal has been thus freed and shotted, the door 21 of the furnace is now brought into register with the product car 22 whereupon the reduced metal and gangue is transferred into said car by gravity. Steam having been admitted through the pipe 24-, it permeates the mass, drives out any air that may have entered the same, and thus effectually prevents the reoxidation of the shotted metal, while at the same time it rapidly cools the hot mass to a point below that at which the metal could oxidize in the It is an important feature of this invention that I employ steam or hot water from which all free oxygen has been driven, to prevent the reoxidation of the freed metal, while it is hot, and until it has reached a temperature at which no appreciable or injurious oxidation can occur. The mass being thus cooled out of contact with free oxygen and moisture it is c'arriedto the granulator where it is subdivided to the required mesh and subjected to the action of a water concentration table, where the shotted metal is separated from the gangue.

T prefer to employ a slight excess of carbon in the furnace over that theoretically required, in orderto insure that a reducing atmosphere will be maintained at all times in the furnace.

in the case of sulfid and some other ores, T prefer to subject them first to the waste sulfurizing process in a furnace preferably of the McDougall type whereupon they may be converted into oxids and then treated according to the process above disclosed.

It will now be clear that by following the procedure above outlined, I am enabled to separate metals from their oxids (except those uniting with carbon to form carbids at the temperature employed) by a procedure which is direct, without the employment of fluxes, or the making of slag, or the converting of mattes. In fact, it will be seen that this procedure enables one to produce the metal from the ore in a single operation and at a comparatively low temperature and in such a condition that a minimum loss is en tailed due to flotation in the separators. It will also be clear that by the treatment with steam or hot water I effectively prevent the reoxidation of the freed metal.

When employing oxidized ores consisting. of or containing large percentages 'of carbonates, such as carbonates of cop er, for example, I may expel the CO and tie H O molecules in any suitable manner, such as by preheating the charge or I may introduce said ores into the furnace and expel said molecules while raising said ores to their reducing temperatures.

It is obvious that those skilled in the art may vary the details of the process Without departing from the spirit of the invention and therefore I do not wish to be limited to the above disclosure except as may be required by the claims.

What I claim is:

1. The process of producing metal free from metallic oxide in ores which consists in heating said ores in a furnace to substantially their temperatures of reduction; adding carbon to said heated ore to reduce the same and to liberate carbon monoxid gas in said furnace; closing'said furnace; causing the pressure to rise sufficiently to cause said gas to penetrate the interstices of said ores and liberate suflicient heat to change the freed metal from a fibrous to a shotted condition; and recovering said metal while preventing a reoxidation of the same, substantially as described.

2. The process of producing ,metal free from metallic oxids in ores whose values consist of said oxids, which consists in heating said ores in a furnace to substantially,

but somewhat below their temperatures of melting; adding carbon to said heated ore to reduce the same and to liberate carbon monoxid gas in said furnace; closing said furnace; causing the pressure to rise sufficiently to cause said gas to penetrate the intersticesof said ores and liberate sufiicient heat to change the freed metal from a fibrous to a shotted condition; stirring the charge to cause said metal to agglomerate; and recovering said metal while preventing a reoxidation of the same, substantially as described.

3. The process of producing metals from ores containing the oxids of said metals, except metals capable of combining with carbon at the temperatures employed, Which consists in heating said ores in the presence of air to points just below the temperatures of fusion of the metals in the ore charge; adding suflicient carbonaceous fuel to reduce all the oxide present, thus freeing the said metals and producing carbon monoxid gas in the furnace; maintaining said gas in said furnace at a pressure sufficient to cause it to penetrate the interstices of the ore while permitting the exothermic heat generated to raise the temperature of the charge to the fusion points of the metals present; suitably stirring said charge while the fusion is taking place to agglomerate the freed metals; and suitably recovering said metals from the gangue, substantially as described.

I. The process of producing metals from a metallic oxid in an ore which consists in heating said ore to a point just below the fusion temperature of the metal present; adding suflicient carbon to reduce all the metal oxld present while excluding the air and maintaining a pressure in the furnace hi her than that of the atmosphere and sufficient to cause the heat evolved to raise said metal to its fusion point; stirring the charge during the reducing action to facilitate the reduction of the mineral and the agglomeration of the freed metal particles; discharging the mass into an atmosphere of water vapor to prevent a reoxidation of the reduced metal; and suitably recovering the: metallic values, substantially as described.

5. The process of producing metals from a metallic oxid in an ore which consists in heating said ore to a point just below the fusion temperature of the metal present; adding sufiicient carbon to reduce all the metal oxid present and to liberate enough carbon monoxid gas in the furnace to evolve sufficient heat to raise said metal to its fusion point; maintaining the evolved carbon monoxid gas at a predetermined pressure above the atmosphere to facilitate the reduction; stirring the charge during the reduc ing action to facilitate the reduction of the mineral and the agglomeration of the freed metal particles; discharging the mass into an atmosphere of water vapor to prevent a reoxidation 0f the reduced metal; .and suitably recoveringthe metallic values, sub stantially as described.

6. The process of (producing metallic copper from an oxidize copper ore which consists in heating said ore to substantially 17 00 F.; adding suflicient carbon to the charge to reduce all the mineral to metal and carbon monoxid as; maintaining the ciently alcove that of the atmosphere to cause the metal to assume a shctted form; agitating the charge to permit said gas to penetrate the interstices of said charge to facilitate the reducing action and to agglomerate the reduced metallic particles; discharging said charge from the furnace in an ance? atmosphere of preheated Water to prevent a reoxidation of the reduced metal; and suita'bly recovering said metal from the gangue, 1 substantially as described.

In testimony "whereof I aifix my signature.

OLIVER B. DAWSON. 

